I. Field of the Present Invention
The present invention relates generally to vehicle transmission shifting apparatus, and more particularly to such an apparatus in which a cable is displaced in response to pivotal movement of a steering column mounted shift actuator lever.
II. Description of the Prior Art
Steering column mounted shifter mechanisms are well-known and provide convenient control for selecting forward, reverse and neutral operational modes which may be available in the vehicle transmission. Such mounting of the shifter actuation lever provides a convenient control position for operation by the vehicle driver, and maintains the actuator lever in an arcuate path of movement which remains recessed behind the steering wheel mounted at the end of the column. While such pivotal or rotary movement of the actuator lever is convenient for the vehicle operator, the linkages through which the shifter lever is connected to the transmission can be very complex.
Some previously known complex linkages include numerous pivoting levers which pivot in response to movement of the actuator lever. However, such lever linkages have components with fixed geometries and thus can require substantial room for displacement of the levers making up the linkages. Another form of shifter includes a rotating shaft which pivots about its axis in response to pivoting movement of the actuating lever. However, such shafts must be torsionally and longitudinally rigid in order to operate effectively, and thus can be bulky and substantially increase the weight of the vehicle shifter mechanism. In any event, forces applied to the shifting mechanism must often be translated in various directions, depending upon the position of the transmission within the vehicle and such change in the direction of the applied forces substantially increases the complexity, as well as the strength and space requirements of the shift linkages.
Although displaceable cables are a well-known type of mechanical actuator, they are not well adapted for use with steering column mounted shift arrangements. In particular, cables are not well adapted for use with previously known steering column mounted shifters for the reason that a cable may be required to change direction numerous times before reaching the transmission. In order to avoid sharp bends in the cable, it may be necessary to occupy a substantially larger space about the steering column of the vehicle to provide less abrupt variation in the longitudinal direction of the cable. In any event, it has not heretofore been possible to apply longitudinal movement of a cable with previously known shift actuators adapted to be conveniently mounted to the steering column of the vehicle.